// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';

// import 'colors.dart';

/// Used with [TabBar.indicator] to draw a horizontal line below the
/// selected tab.
///
/// The selected tab underline is inset from the tab's boundary by [insets].
/// The [borderSide] defines the line's color and weight.
///
/// The [TabBar.indicatorSize] property can be used to define the indicator's
/// bounds in terms of its (centered) widget with [TabIndicatorSize.label],
/// or the entire tab with [TabIndicatorSize.tab].
class LUnderlineTabIndicator extends Decoration {
  /// Create an underline style selected tab indicator.
  ///
  /// The [borderSide] and [insets] arguments must not be null.
  const LUnderlineTabIndicator({
    this.borderSide = const BorderSide(width: 2.0, color: Colors.white),
    this.insets = EdgeInsets.zero,
  }) : assert(borderSide != null),
       assert(insets != null);

  /// The color and weight of the horizontal line drawn below the selected tab.
  final BorderSide borderSide;

  /// Locates the selected tab's underline relative to the tab's boundary.
  ///
  /// The [TabBar.indicatorSize] property can be used to define the
  /// tab indicator's bounds in terms of its (centered) tab widget with
  /// [TabIndicatorSize.label], or the entire tab with [TabIndicatorSize.tab].
  final EdgeInsetsGeometry insets;

  @override
  Decoration lerpFrom(Decoration a, double t) {
    if (a is UnderlineTabIndicator) {
      return LUnderlineTabIndicator(
        borderSide: BorderSide.lerp(a.borderSide, borderSide, t),
        insets: EdgeInsetsGeometry.lerp(a.insets, insets, t),
      );
    }
    return super.lerpFrom(a, t);
  }

  @override
  Decoration lerpTo(Decoration b, double t) {
    if (b is UnderlineTabIndicator) {
      return LUnderlineTabIndicator(
        borderSide: BorderSide.lerp(borderSide, b.borderSide, t),
        insets: EdgeInsetsGeometry.lerp(insets, b.insets, t),
      );
    }
    return super.lerpTo(b, t);
  }

  @override
  _UnderlinePainter createBoxPainter([ VoidCallback onChanged ]) {
    return _UnderlinePainter(this, onChanged);
  }
}

class _UnderlinePainter extends BoxPainter {
  _UnderlinePainter(this.decoration, VoidCallback onChanged)
    : assert(decoration != null),
      super(onChanged);

  final LUnderlineTabIndicator decoration;

  BorderSide get borderSide => decoration.borderSide;
  EdgeInsetsGeometry get insets => decoration.insets;

  // Rect _indicatorRectFor(Rect rect, TextDirection textDirection) {
  //   assert(rect != null);
  //   assert(textDirection != null);
  //   final Rect indicator = insets.resolve(textDirection).deflateRect(rect);
  //   return Rect.fromLTWH(
  //     indicator.left,
  //     indicator.bottom - borderSide.width,
  //     indicator.width,
  //     borderSide.width,
  //   );
  // }
  // Rect _indicatorRectFor(Rect rect, TextDirection textDirection) {
  //   assert(rect != null);
  //   assert(textDirection != null);
  //   final Rect indicator = insets.resolve(textDirection).deflateRect(rect);

  //   //希望的宽度
  //   double wantWidth = 60;
  //   //取中间坐标
  //   double cw = (indicator.left + indicator.right) / 2;
  //   return Rect.fromLTWH(cw - wantWidth / 2,
  //       indicator.bottom - borderSide.width, wantWidth, borderSide.width);
  // }
  @override
  // void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
  //   assert(configuration != null);
  //   assert(configuration.size != null);
  //   final Rect rect = offset & configuration.size;
  //   final TextDirection textDirection = configuration.textDirection;
  //   final Rect indicator = _indicatorRectFor(rect, textDirection).deflate(borderSide.width / 2.0);
  //   final Paint paint = borderSide.toPaint()..strokeCap = StrokeCap.square;
  //   canvas.drawLine(indicator.bottomLeft, indicator.bottomRight, paint);
  // }
  void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
    assert(configuration != null);
    assert(configuration.size != null);
    double height = 10;
    double _width = 18;
    if (_width > configuration.size.width)
      _width = configuration.size.width / 3;
    canvas.drawLine(
    Offset(offset.dx + (configuration.size.width - _width) / 2, configuration.size.height - height / 2),
    Offset(offset.dx + (configuration.size.width + _width) / 2, configuration.size.height - height / 2),
    Paint()..strokeWidth = height / 2..isAntiAlias = true..strokeCap = StrokeCap.round..color=Color(0xFF00AB84));
  }
}
